RAID (redundant array of independent disks) is a storage technology that combines multiple disk drive components into a logical unit. Data is distributed across the drives in one of several ways called “RAID levels”, depending on the level of redundancy and performance required.
RAID is used as an umbrella term for computer data storage schemes that can divide and replicate data among multiple physical drives: RAID is an example of storage virtualization and the array can be accessed by the operating system as one single drive. The different schemes or architectures are named by the word RAID followed by a number (e.g. RAID 0, RAID 1). Each scheme provides a different balance between the key goals: reliability and availability, performance and capacity. RAID levels greater than RAID 0 provide protection against unrecoverable (sector) read errors, as well as whole disk failure.
A disk array controller is a device which manages the physical disk drives and presents them to the computer as logical units. As is understood, a disk drive is a common term that includes, but is not limited to NAND Flash SSD's and other non-volatile memory devices. It almost always implements hardware RAID, thus it is sometimes referred to as RAID controller. It also often provides additional disk cache. A disk array controller name is often improperly shortened to a disk controller. The two should not be confused as they provide very different functionality.